The Almost Empty House
by Rachel Indeed
Summary: An alternate universe story, set in the Harry Potter universe.  Sherlock and John are on their way to Hogwarts.  Sherlock is determined to live in an empty House, but things don't work out according to plan.


_Disclaimer: Thank you Mssrs. Doyle, Moffat, and Gatiss. Mischief managed!_

**The Almost Empty House**

The scarlet train stood idling on the track.

John climbed aboard, moving toward the farthest end. His father's wand – oak and dragon heartstring – felt warm and awkward in his hand. He'd never used it, apart from that one giddy swish of sparks that proved it a match for him.

The Watsons had arrived at Platform Nine and Three-Quarters neither early nor late, so as John worked his way down the aisle he wasn't surprised to see most of the compartments occupied but not yet overfilled. He paused in the final car and picked the corner farthest from the loo on the assumption that any pranks were most likely to explode from that quarter.

Sliding back the glass door, he nodded politely to the two boys already seated by the window. One, a baby-faced bloke with square-rimmed glasses and a friendly smile, waved him in. The other, wrapped around a book, took no notice.

John smiled and nodded to the friendly boy, who said quietly, "Mike Stamford. How d'you do?"

"Good, thanks. John Watson." John bunged his case up onto the storage rack and picked a seat on Mike's side of the compartment, sensing that the reader needed his space. He was just about to plop himself down when a sharp voice warned, "Best not to sit on the toad, John."

Startled, John caught himself on the overhead shelf and turned to scan the seat cushion beneath him. He saw nothing.

"What? Oh!" Mike reached out both hands to run them over the upholstery, looking surprised. "I walked into the middle of a tiff between a couple fourth years in the next car over. Went invisible for a minute, but a prefect saw it happen and helped me out. I didn't realize Murray had gotten caught, too." His fingers struck an invisible, apparently squirming bundle on the seat, and he lifted it gently and cradled it to his chest. "I'll just run and find someone to fix him," Mike said. "Back in a tick." Pulling the door open, he added, "Ta, Sherlock."

The other boy raised one finger slightly from where it rested on the spine of his book and then flipped to the next page.

The train shuddered into movement, so John lowered himself to his seat and spent a second fidgeting before deciding to skip the introductions. "Thanks," he said instead. "That would've been messy. How'd you know it was there?"

"I was listening for it," Sherlock said, still reading. "The Disillusionment Charm lingers at extremities, you know, and when Mike walked in two of his fingernails were missing. It was obvious he'd been through a recent bout of invisibility, and when I saw the fabric of his pocket move on its own it was clear that his pet was still affected. Climbing out of his pocket, that meant toad or rat, so I listened and eliminated rodent when no scratching sound accompanied its movement. Toads generally prefer to remain relatively close to available body heat, especially in an over air conditioned car like this one, so the seat next to Mike was the most likely spot for it to settle." He lowered his book marginally. "Sherlock Holmes, by the way."

"Hi," John said, a bit bewildered. "That was clever."

"Hardly," Sherlock said.

"Are you and Mike mates, then?"

"We met last summer at a nature retreat our parents forced us to attend." Sherlock pronounced _nature retreat_ in a tone most people reserved for terms such as _death camp_. "His dad thought he needed to lose weight and my mum thought I needed more sunshine. We hid out in the woods and he melted teacakes while I collected soil samples, so we managed to salvage something from the ordeal. He's a decent sort."

John smiled, but he could hear boredom in Sherlock's voice so he simply nodded and let the conversation drop.

In another second the boy was back behind his book and Mike was clambering through the door with a very ugly toad in hand. He also brought a bit of company: a girl their own age and a boy who looked a few years older. "Hey, lads," Mike said, "this is Sally and Greg – Greg gave me a hand with Murray but some tosser swiped his seat while he was up, so I invited him back with us. Sally just made the train! It was amazing, I saw her jump up the steps at the last second." He sounded impressed, but Sally blushed. "Anyhow, this is Sherlock Holmes and John Watson."

"Hey," John said, scooting over to the window to make room.

There was a moment of bustle as everyone settled, and somehow by unspoken agreement the seat next to Sherlock stayed empty. He didn't look up.

"Fancy a round of Exploding Snap?" Greg asked, pulling out a deck from his pocket and generally acting as though getting stuck with a group of first-years was no hardship. John liked him immediately.

"I've never played," John admitted. "We're not allowed at home, but I can watch until I learn."

"No need for that," Greg said, "a troll could learn these rules in about a minute. It just takes a light touch, that's all. You want in?" he asked Sherlock, pausing in his dealing.

"Not at all." Sherlock scribbled something in his book – a library book, John noted. He'd better hope they learned a spell for erasing ink in the next week.

Greg shrugged and moved on, but Sally looked over with a frown. "Oh, that's nice," she said. "You haven't even said hello."

"True," Sherlock said.

"What, you can't be bothered?"

Sherlock flashed a smile so obviously fake it had to be intentional, and flipped another page. John thought it was a bit stupid. Picking fights wasted more time than playing nice, especially if you were all going to be stuck on a train for hours_._

But then Sally reached over the empty seat and made a grab for Sherlock's book, which was even stupider and crossed the line into actual bullying. So John snapped the corner of the playing card in front of him.

A _whoosh_ of magical flame jetted across toward the combatants, singeing John's eyebrows on its way. Sally pulled back with a startled shriek and Sherlock jerked the book protectively against his chest.

"Sorry, sorry," John said, waving smoke at both of them. "Oh, perfect, there goes half my tie. Mind if I open the window?"

He and Mike made a bit of a production out of undoing the latches and lifting the glass, and the compartment had literally and figuratively cooled off by the time they sat down again.

"So," Greg said into the ambient awkwardness. "Maybe best to save the card game for later, then."

Mike, bless him, stepped into the breach. "So what House are you in, Greg?"

"I'm Gryffindor, myself – I'd say that's the friendliest place for Muggleborns, if any of you were worrying about that. In other Houses – except Slytherin – they ignore it, but in Gryffindor it's actually cool. So that's worked out well for me. Things can get a bit rowdy, but we're a nice lot, overall. I think I might know your sister, John. Short, cute, wears her scarf everywhere? Steamrolls through corridors like she never learned to brake?"

"That's Harry," John nodded. "She loves being a lion."

"Is that where you're headed, then? Keeping it in the family?"

John shifted slightly. "Dunno," he said. "I guess I'll find out soon enough."

"I think I'm a Hufflepuff," Mike admitted, as though it were embarrassing. "But I'd like to make it into Ravenclaw. If I'm, you know, smart enough."

John frowned a bit, but Greg answered calmly, "You get more of a choice than you might think. Make sure and speak up about what you want, yeah? Don't be shy."

Mike looked encouraged. Turning to Sherlock, he asked, "What House are you heading for? I bet you could have any one you want."

John saw Sherlock's quick smile, genuine this time, but closed off rather than directed outwards. The question was a private joke to him, then.

"Guess," he dared them.

"You're a snake," Sally huffed. "No question."

The crinkle of Sherlock's nose said, _Obvious. Unspeakably dull_.

"Ravenclaw?" Greg offered, eyeing Sherlock's book and extending the benefit of the doubt. Maybe his intelligence was of a scientific rather than ruthless sort. John thought this was a bit optimistic. Judging from the tilt of his eyebrow, Sherlock did, too.

"Gryffindor," Mike announced, clearly considering the idea a compliment. Sherlock rolled his eyes, but there was a hint of affection in the gesture.

No one else was going to be a taker on Hufflepuff; it was simply, indisputably wrong. John shrugged. "Hufflepuff," he said, in part to be contrary, in part because Hufflepuff didn't deserve to be left off the roster just because its virtues weren't popular. But mostly because a private joke couldn't work without a set-up, and he could sense, somehow, that this was the set-up.

Sherlock delivered the pay-off with satisfied flair. "You're all wrong."

John obliged. "We can't _all_ be wrong. There are only four Houses."

Sherlock shrugged. "It's a serious mistake to twist facts to fit theories instead of theories to fit facts. I am a fact. I have no intention of twisting to fit anyone's cookie-cutter system." He settled back into his seat. "I'm going to be my own House."

Mike looked horrified. "But they'll throw you out if you can't be properly Sorted!"

"Nonsense."

"But what will you do? Where will you _sleep_?" Greg focused on the practicalities. "You won't have a soul to talk to, you won't even have a Quidditch team!"

"I daresay I can bear the loss."

"Talk sense," Sally said, disgusted.

"I never talk anything else. I'll be fine on my own."

"I'm not sure I agree," John said and found himself sitting at the center of sudden and absolute focus, shifted painfully from background to foreground.

"Why not?" Sherlock asked, and though his eyes were half-lidded his tone was encouraging.

John considered being politely vague, but his instincts told him that would be a mistake. This kid wanted blunt; he was starving for it. "Dunno. I just figure there are probably lots of things that don't seem sensible to you." _Like every one of us, for starters_. "If you took your own stand on everything, you'd wear yourself out in a week. So why pick a fight over the House thing? It's not like it'd hurt you to be Sorted. It might even help, to have people who'd back you up even if they didn't agree with you." John's left hand worried absently at the loose thread on his sleeve. "Better to pick your battles, I'd say."

"Is that what you learned from your father?" Sherlock asked, his voice precise and distant. "After he died in the war, once you were old enough to understand, you thought about battle a lot. You thought about how things might have been different if your mum had been there to Heal him, if she hadn't stayed away from the front lines because someone had to be there to care for you and your sister. You know you want to Heal, but there's a part of you – a big part – that wants to fight."

John's whole body was tensed in shock, the compartment dead silent, and Sherlock's dream-like monologue shifted sharply into facts and figures. "Did you know that your chance of finding employment in any dangerous or high-pressure career is reduced by thirty-five percent if you're sorted into Hufflepuff? The statistics are there to prove it. Fifty-eight percent of Healers are Ravenclaws, seventy-one percent of Aurors are Gryffindors. Slytherins and Hufflepuffs barely make it through the door, they're tripped up by too many preconceptions."

Sherlock leaned forward and pressed his fingers tip to tip, flat and intense. "The House system offends me because lazy thinking offends me, plus I get more than my fill of social engineering at home. I'm not signing up for more. If given a chance, that system would slap me in Slytherin without a second thought, and I might never get the chance to choose the battles I want. I'm chucking the whole thing. And if I were you, I'd stop being stubborn about Hufflepuff and aim for Gryffindor. If you're going to kowtow to archaic conventions, might as well make them work for you."

Having finished, the life in his face flicked off; he turned his head away. His nose went white as he pressed it to the window, and he was back in his own world.

John breathed deep and even, very still.

"That's not right," Sally said.

"Look, it's…" Mike started, but she didn't pause. She looked genuinely upset.

"It's not fair to use magic on someone without asking, pull out the inside of their head just for kicks. It's messed up. You shouldn't be able to _do_ that."

"It wasn't magic," Mike said, patting at John's shoulder. "Really, he wouldn't…"

"I hope you do get kicked out!"

"And I hope you manage to kick your smoking habit," Sherlock rejoined, sounding a million miles away. "Your parents must be blind not to have spotted it by now, but the next time you bung off for a quiet fag, you shouldn't cut it so close. You almost missed the train."

"Stay out of my head, you freak!"

"I saw a quarter mile post, but…No, it's no good, I can't calculate the velocity from this angle," he muttered. Standing abruptly, he headed out the door.

It slammed behind him.

"Sorry," Mike said after a moment. "I guess I should have warned you. He's always like that."

* * *

Half their class had been Sorted before Sherlock was called to his turn. John watched as he took his seat on the stool, looking perfectly collected. Just before Professor McGonagall lowered the Hat to his head, he smiled.

It was silent for two minutes, then three. Four minutes, then five.

All the tables were alive with whispers, but John stayed focused, his fingers clenched.

Everyone jumped when the booming croak finally came. "A NEW HOUSE FOR THIS ONE, ALBUS."

In the face of general disbelief, the Headmaster merely looked intrigued. He walked over to the platform at the head of the steps and eyed Sherlock with a slight smile. Sherlock met his gaze without expression and held out the Hat.

"Thank you, Mr. Holmes," Dumbledore said. "I believe a brief consultation is in order."

The headmaster plopped down on the Sorting stool and slipped the Hat on. He pulled a yo-yo out of his pocket and absently walked the dog through a dozen cat's cradles, nodding occasionally.

"Excellent," he said finally. "Irregular and ridiculous. I love it."

He plucked off the Hat and turned to Sherlock. "Well done, young man. I admire original thinking and shall certainly watch your career with interest. For the future you may regard me as your Head of House. This means I shall attend to any disciplinary issues that may arise, and you may also feel free to consult me regarding any scholastic matters on which you require advice."

"I shan't require advice," Sherlock said calmly. "On anything."

"Indeed." Dumbledore waved with his odd, knotted wand and a new table, small and circular, sprang into being. "Won't you have a seat? I'm afraid we do have the rest of the Sorting to finish before we can get to the raspberry tart, which I expect to be the highlight of the evening."

Sherlock crinkled his nose, but descended to his new seat without argument. The eyes of the school followed him.

"Molly Hooper," McGonagall called, sounding a bit strident.

And they went back to business as usual.

Sally had gone proudly to Gryffindor – Greg had smiled and saved her a seat. Mike did make it to Ravenclaw, and John offered a grin and thumbs up as he passed. There was only one other kid left when John took his seat and felt the ancient fabric, rasping and dry, drop over his eyes.

"A strong mind," the dismal voice whispered, sounding loud inside his head. "But a better heart. There's courage here, and chivalry, plenty of ambition, but for what? To help, to save. And yet…you have questions, doubts. There's disillusionment, stubbornness, lurking right under the surface. Anger. And more than a touch of danger in you, John. On any other day I'd be yelling Gryffindor right about now, but I can see what you want. Why don't you say it? You don't like people making your choices for you, after all. I have to tell you, that may be a problem if you're serious about following him."

"No, it won't be."

"So sure you can hold your own?"

"Pretty sure, yeah."

"Good lad. I could try to reason with you, but everything I have to say has already crossed your mind."

"Er, right. And…my answer's crossed yours?"

The Hat actually chuckled, low and scratchy in John's mind. "He will be great, you know, it's all in his head. But you can help him on the road to something more than greatness."

"What d'you…"

"You're a good soul, John Watson. I can see you'll do very well in THE NEWLY INSTITUTED HOUSE THE HEADMASTER HAS NEGLECTED TO LABEL."

The Great Hall erupted for the second time that night.

* * *

Sherlock wasn't speaking to him. He'd suffered through the Feast in resentful silence, picked at his food, and flatly refused to sing the Hogwarts anthem. John let him simmer, thoroughly enjoyed the meal, and belted out his share of school spirit to the tune of McCartney's _Paperback Writer_.

Dumbledore led the two of them to a corridor on the seventh floor, passed three times by a stone wall, and opened a door which appeared by the tapestry. Inside were spacious living quarters, a warm fireplace, a jumble of scientific equipment, and some quite old-fashioned wallpaper.

"This is the Room of Requirement," Dumbledore explained. "In order to enter, make three circuits while mentally specifying your requirement. I used the phrase 'I need appropriate quarters for John and Sherlock.' If you do the same, you should have no trouble returning to these rooms."

John had dressed for bed and was mostly done flossing when Sherlock finally voiced his complaint.

"I wanted to live in an empty House."

John sighed. "Well, you shouldn't have said all that stuff to me on the train, then."

"What I _said _was to stop being stubborn and choose Gryffindor!"

"Yeah, which made choosing Gryffindor into a kind of cowardice. Funny how that works."

"How was I supposed to know you'd notice something as rational as self-contradiction, let alone care about it? I think aloud all the time, none of you cretins ever _listen_."

John closed the medicine cabinet with unnecessary force. "Right. Okay."

He went to bed. As far as he could tell, Sherlock didn't.

Sherlock was nowhere to be seen the following morning, and John was heading downstairs to breakfast when he noticed the disembodied head in the fireplace.

"Yaaaarrrraaahhh," John shouted, dropping all five of his textbooks.

"No need to be alarmed," the head said, sounding quite posh.

"What, how?…"

"The pertinent question, I think you'll find, is 'who?'" the head said. "I'm a recent graduate, of considerable influence, who finds it much easier to get up each morning and make my way in the world if I know exactly what Sherlock Holmes is up to. Kindly oblige me."

"Say again?"

"Tell me about his latest fiasco. I had arranged rudimentary spy networks in all four Houses but failed to make provision for this eventuality." A sliver of shoulder, just visible under the grate, twitched irritably. "Live and learn. In terms of useful intelligence, I find myself at loose ends, and I don't mind saying that is an uncomfortable novelty."

"Piss off." John reached out to close the flue.

"Don't," the head said, and its voice stopped John's hand. He'd stepped back two paces before his brain remotely caught up. Embarrassed, he reversed himself, crouching down to confront the fireplace-man more directly.

"Brave," the head commented.

"What do you care what an eleven-year-old gets up to?"

"But then, bravery is quite the kindest name for stupidity, don't you think?" Without changing his tone, the head added, "I care because he's my brother."

John stayed frozen for a second, then leaned back on his heels. "Well, if you're anything like your brother, I'm sure you've got quite a few names for stupidity."

"Quick judge of character. What is your connection to him?"

"I…don't have one. We just met. Now we're in a House together."

"A House of two, a House entirely of his own creation. I am beyond surprise when it comes to Sherlock, but why did the Hat place you with him? What did it tell you?"

"I could be wrong," John said, "but I think that's none of your business."

"It could be."

"It really couldn't."

Dark eyes flicked over him, and John began to see the family resemblance. "You have steady hands, young Mr. Watson," the head said slowly, "but you haven't yet decided how to use them. You've already started to feel at home in your mother's clinic, standing over potions, reading books far too advanced for you. But there's a part of you, perhaps the most powerful part, that wants to see the battlefield like your father did, with his wand in your hand – "

"Could you people stop doing that? Is my family history just written on my forehead, or what?"

"Your instincts are good, to have fastened on my brother as the walking war-zone he is. But really, John, won't you think better of it? What will your mother say? How do you expect to get on in classes, in sports, in any kind of normality? Forgive the cliché, but this is the first day of the rest of your life, and one thing everyone learns quickly at Hogwarts is that it's important not to fall in with the wrong sort. I can help you there. Believe me when I say my brother is the wrong sort for any normal child."

"I think I can tell the wrong sort for myself, thanks."

The head's eyes narrowed. "You're very loyal, very quickly."

"Hufflepuff was my second choice," John said and flashed a smile as fake as Sherlock's. "You've got soot on your tie, by the way. Cheers."

He picked up his books and went to breakfast.

Sherlock wasn't in the Great Hall either. From all available evidence, he neither ate nor slept. Fine.

John thought about sitting alone at their tiny House table for about two seconds, and then ambled off to find Mike and get to know some Ravenclaws. Harry soon invited herself over to tousle his hair and tell him she wasn't surprised he'd found a way to screw up something as basic as the Sorting. But he thought she sounded a little impressed, and she wrapped her scarf around him while swiping his pumpkin juice.

"I know they aren't your colors." She poked his arm. "But…welcome to Hogwarts anyway."

"I can choose whatever colors I like," John grinned, tucking the wool snug around his collar, red and gold trailing down his shoulders. "Thanks."

He finally ran across his Housemate in the queue outside the Transfiguration classroom. Sherlock's eyes lit up momentarily, but John headed him off at the pass.

"Not a Gryffindor," he clarified. "Just dressed like one."

"I thought you might have had second thoughts."

"Nope. You'll just have to live with me. That reminds me, though, your brother says hi."

Sherlock stared at him as though he were something unexpected, practically exotic.

That was new.

The classroom door swung open unassisted, but the room turned out to be empty save for a grey cat perched imperiously on the desk. There was no notice of assigned seating and no sign of their professor. John was getting ready to settle somewhere around the fifth row, just behind a sweet-looking Hufflepuff girl, when Sherlock caught him by the elbow and propelled him straight to the front.

"Hey!" he protested, but somehow he had already been bodily deposited on the left-hand side of the room's central worktable, and Sherlock was sitting beside him.

"Good morning, Professor," Sherlock addressed the cat. "I'm petitioning the Headmaster for permission to move on to the OWL curriculum immediately, but until the paperwork goes through I'm prepared to assist my Housemate here," he waved a hand at John, "with the basics. I thought we might start with the elementary principles of mass-energy conversion paired with a bit of practical experimentation. I've frankly never seen the point of wasting energy on pincushions and porpoises, but I'm willing to teach him to create tea from the inanimate object of your choice. It's a life skill that will come in handy, I'm sure. Though if you insist on the unnecessary complication of saucers and patterned china, I may be unable to collaborate. Plain mugs are far more practical."

John and the cat stared at him, nonplused. After a moment the cat sprang forward and shifted into the same severe woman who had presided at their Sorting. The exasperated expression John remembered was significantly more alarming up close.

"Mr. Holmes," she said, "I appreciate your enthusiasm, but we are starting with the basics today. Hatpins into spoons. Everyone in this classroom is to focus on that task, and only that. If you demonstrate mastery of Transfiguration at this grade level, I will encourage the Headmaster to allow your transfer. Now, ladies and gentlemen, I would ask you all to open your textbooks to page six and review the instructions."

John flipped his book open while Sherlock muttered something unintelligible about "deletion" and "simpletons" and possibly "reinventing the wheel." John tried to tune him out.

An invasive hand commandeered his book before he was halfway through the first paragraph, and Sherlock no more than glanced over the text before saying, "I dumped these specifics long ago, but we can still start with theory."

"_Sherlock_…" John could feel that sentence starting to go somewhere bad and gritted his teeth. "Thanks and all," he forced out, "but I'm not your…project."

Sherlock blinked. "No, you're my Housemate. I just said so."

Ah, John thought.

At some undisclosed moment over the course of Sherlock's morning John had graduated from an objectionable idea to an established fact.

Interesting.

"Now, John, the first step is to build up potential energy – " Sherlock lifted his wand from the desktop, drawing a precise parabolic line which reached its apex about four inches above his eye line, " – and then transfer that potential to kinetic energy." Sherlock vigorously swished the wand downwards, flicking his wrist outward. "This energy can then be used to induce matter conversion through the medium of Latin incantation. Repeat after me…"

"Mr. Holmes!" Professor McGonagall looked positively stormy. "There is only one teacher in this classroom. I will be responsible for providing Mr. Watson with age-appropriate instruction, along with everyone else. Please read the instructions as I asked and stop these interruptions. Five points from…"

She floundered for a moment, then said, "Please remain after class for a ten-minute detention."

Professor McGonagall proceeded to demonstrate the "swish and flick" wand work necessary for the spell, then set them loose to practice.

Sherlock looked scandalized. "But they won't understand _why_ it works!"

"I am teaching them to perform magic, Mr. Holmes. Understanding the principles of magical theory will come later."

John made quick progress, but Sherlock was fuming. "You deserve better than this," he insisted, not bothering to lower his voice. "Don't worry. We'll talk about it when we get home."

"Mr. Holmes, you are disrupting this class. Mr. Watson," McGonagall said, "kindly pick up your books and move to a separate desk."

And so the week went. In every class Sherlock attached himself to John and made persistent trouble with the professors. Snape was the only one who assigned him full length detentions for being an insufferable know-it-all, but McGonagall and Kettleburn were on the edge. However, traditional detentions – like all traditional forces – backfired around Sherlock. He came back from a four hour stint in the Potions dungeons with several pockets full of rotting flobberworms which he proceeded to cultivate in the bathtub.

John tried suggesting that Sherlock needn't be quite so aggressive in looking out for his academic interests. He told him it was perfectly fine if he wanted to partner with more advanced students.

Sherlock would have none of it. "Everyone partners with people in their own House. It's _normal_."

As friendships went, it was clumsy. But Sherlock had to learn somehow.

John let him teach.

* * *

"How did you know all about me, that first day on the train?"

They'd made it through two weeks without killing each other, and John really couldn't hold back the question any longer.

Sherlock lit up like Christmas had come early, not impatient or disdainful at all. Seeing him, John wished he'd just asked about it straight off.

"Let me think," Sherlock said. "I usually don't have to break it down. I never explain anything at home, everyone already sees and they just tell me if I'm right or not."

He lifted his hands to his chin, palm to palm.

"Where to start…maybe the Healing? That seems most obvious. The rest is more speculative, probabilities rather than facts. Yes. I'll give you the evidence first. Let me just line it up for a second."

John watched him – he looked like he was doing a math equation in his head.

"Okay," Sherlock breathed, and then his voice smoothed out, picking up momentum as it ran. "When you walked into the train compartment you brought the smell of dittany with you, faint but detectable. It's saturated your clothes, too deep for any wash to fully clear. Dittany is the most common ingredient in potions which knit bone or muscle, and it also forms the base for Dreamless Sleep and a number of other treatments for psychological as well as physical wounds. Inference: you frequently brew healing potions or live in an environment where someone else does. You don't exhibit any of the classic physical or emotional signs of abuse, so it's unlikely that you make these potions for yourself or receive them from professionals for your own treatment. Inference: you come in contact with potions being brewed for other patients, particularly those experiencing mild to moderate trauma. Probability: a parent works in or runs a clinic.

Secondary evidence: there is a callus in the crook of your left thumb where you have habitually rolled bandages – a helpful chore which you could do around the house without the use of magic. There are two potion stains of different ages and colors on your shoes, which you have covered – badly – with ink. You said you aren't allowed to play Exploding Snap at home, which implies the presence of unusually flammable materials in the house. Your nails are meticulously trimmed and your hair is unusually short – such precautions are common for those exposed to infection or hazardous chemicals. Finally, you have an unusually calm demeanor in the face of aggressive and dismissive personalities. Conclusion: your parent runs a clinic from your home, has encouraged your interest in medicinal potions, and expects you to navigate amongst agitated patients with maturity and respect."

"That…that is amazing."

"You think so?"

"Of course it is. Unbelievable."

Sherlock actually blushed.

"But how did you get the stuff about my dad, and the war?"

"Ah, that was in your wand."

"My wand? I wasn't even holding it."

"It was in your pocket. It's beautiful oak, polished and well cared for, but it has seen years of use and the pattern of wear along the handle clearly shows the imprint of longer fingers than yours. It's been worn smooth in the hand of a grown man. There are scratches and nicks and a quite conspicuous charring along the right side near the handle where the kill shot hit. That wand has been through a war, a brutal one. It was afterwards preserved and polished – a family heirloom, then. You have an older sister, a Gryffindor who "never learned to brake," and yet this wand was reserved for you. Odds are that it's father-son symbolism; most families indulge that sentiment when it comes to the relics of war. And yet this wand – damaged in battle and tempered with loss – had to fit you, had to choose you as compatible. That implies an underlying similarity of temperament between you and your father, a shared affinity for the risks of the battlefield. How did you gain such an affinity? There's no way to be sure, but you would have been no more than an infant when the War ended; you've had your whole life to watch your mother heal other people and remember the one person she couldn't save. She wishes that she'd risked following him into that last fight, and so do you. Your instincts are dead set against caution, aren't they?"

John had inherited his father's wand and his mother's potions and a bone-deep anger at the injustice of life which he managed very carefully. He looked across the room at Sherlock and thought _I follow you now._

"I guess they are," he agreed.

* * *

John came downstairs to find Sherlock sitting on the floor in a blizzard of paper.

"I'll probably regret asking this, but what are you working on?"

"I'm choosing a motto for Holmes House. I've got seven viable options so far, but I'm inclining to: _Res pro ratio. Haud later vacuus clay. _Facts before theory. No bricks without clay."

"This is not Holmes House."

"Logically it should be named after me; I founded it."

"That is so not on. I'm not spending my next seven years as a Holmes, that's rubbish. And I'd get rid of that list if I were you; if anyone finds out you spend your spare time writing free-style Latin they will force you into Ravenclaw."

"A simple motto is a perfectly…"

"No. Just no."

After an irritated monologue, an accidental sofa levitation and a brief interlude of sulking, Sherlock agreed to consider a compromise.

"Look," John said, "Dumbledore had it right when he called this whole thing irregular. Let the profs call us the Irregulars, why don't you? Everyone else will call us whatever they want anyhow."

This turned out to be perfectly true.

"What've you got against Slytherin?" John asked, two months in.

"What makes you think I've got anything against Slytherin, in particular?"

"You don't like any of our professors, but Snape's the only one you actively antagonize."

"I don't antagonize him. I don't have to. He lives in a natural state of antagonism."

"Well, it doesn't help that you constantly steal from his storeroom."

"It hardly qualifies as stealing when the only bar he placed on the door was a 'logic puzzle' any five-year-old could solve."

"Everyone's a critic."

Sherlock huffed, bent low over the beakers of stolen chemicals bubbling on their kitchen table.

"I know it's more than just Snape, Sherlock. Spill."

Sherlock added three perfect drops of rosewater to his potion, shoulders tense and hand steady. "My brother was the Slytherin poster child – seven years of impeccable amoral achievement, backstabbing his way to Head Boy. Keeping up his precious manners, simpering even at the top."

"Could've done worse, couldn't he?"

"He could have done much worse, but at least that would have been more interesting – more _honest_ – than filling his days with petty power games and carefully-crafted mediocrity. I can fake normalcy if I need to. But Mycroft does it all the time. It's phenomenally exhausting, it devours his energy. Such a waste."

John tried on this idea. "You mean underneath, he's really like you?"

"Hard to say. I've never seen underneath."

"What d'you mean? He's your brother, he must drop the act with you."

"He ups the act with me. He puts in layers. He thinks he knows what I like and…" Sherlock's fingers twitched and he frowned, setting down his pipette. "…and he loves me. I'm fairly sure. So he gives me Machiavellian twists and light buffoonery to keep me entertained. I ate it up when I was a kid. He arranged himself like a set of Russian dolls, let me crack him open a dozen times over and everything I found somehow fit perfectly inside the whole. It took me years to realize he was humoring me, and years more before I saw that I'd never hit bottom."

Sherlock motored abruptly across the sitting room and threw himself into his chair. "My brother is basically a Boggart. No one will ever know what he's like when he's alone, but when he's with you he'll be reading your mind and reflecting the pieces he wants you to see. You can trust him to be careful, but not to be sincere. Ever. He's _always_ trying to influence you in one direction or other. He staged your little fireside chat for my benefit, you know."

"You were there? You heard us?"

Sherlock waved a hand. "Assume I hear everything; you'll usually be right. He was giving you a chance to show your quality, so I'd know who I was dealing with. He doesn't think I'm any judge of character. He barely trusts me to tie my own shoes, let alone pick my own company. It's insulting."

"It is, yeah. But you didn't pick me for company, you got stuck with me. And you'd figured me out after two minutes on the train anyway."

Sherlock spoke under his breath.

"Sorry, what?"

"I said, not quite. But I'd have got there eventually."

John smiled, but Sherlock's face was as dark as he'd ever seen it. "Mycroft's given up his soul for the sake of power and his personality for the sake of influence," Sherlock said. "I've never understood how anyone so fantastically smart could have done something so horribly stupid."

John looked at him, considering. "Anyone who's known you five minutes can tell that's never gonna happen to you."

"No, it's not. I don't shape myself to other people's expectations, bad or good. So don't start, John. Don't you even start."

"Start what?"

Sherlock gave him an odd, angry look, and then went up to his room.

**Epilogue: Excerpts from the Further Adventures of the Hogwarts Irregulars**

_Class work, Year Two:_

They trudged in from Care of Magical Creatures, covered in mud.

"I said I didn't do well with animals. You can't say I didn't warn them."

"Well, you could have warned _me_." John winced as he lowered himself to the sofa. "Why do we even have a demon hound?"

"I can't imagine," Sherlock muttered, once again failing to put on the kettle. "Nice shot, by the way."

_Boggarts, Year Three:_

An older version of Sherlock stepped forward, dressed in a drab brown suit and carrying an umbrella. "Are you _still_ here, John?" he sighed, irritation plain on his face.

John knew he was supposed to be concentrating, but he couldn't. Sherlock had gotten bored with him; properly, finally bored.

"Oh please, can you possibly be that dense?" Sherlock answered his thought. "I haven't _gotten_ bored with you. I've _always been_ bored with you. It amused me to make you think otherwise, for a little while. It's good practice, you know, seeing how far you can push a person's feelings, and yours were simple enough to cut my teeth on. I moved on long ago, but you just keep hanging about. It's pathetic, and I'm sick of it. So let's try the direct approach. Leave me alone, you drab, useless, _stupid_ little…"

With an incoherent yell, the real Sherlock threw himself at the Boggart. Instantly, it spun and shifted, scanning Sherlock's mind for its new form.

As it turned out, its form was exactly the same, and it barely had time to raise its umbrella before Sherlock punched it in the face.

They got full marks – anger effectively dispelled fear – but neither of them were able to laugh about it afterwards.

_Inadvisable experiments, Year Four:_

"Sherlock, is that thing poisonous?"

"Naturally. Swamp adder. Deadliest snake in India."

"Then get the hell away from it!"

"I'm attempting communication. The venom is an excellent incentive to succeed."

"For the last time, you are not a Parselmouth! You can't just put yourself in biting-range and hope the words 'spare me' will kick in! You've got to be born with the gift."

"Wrong. Dumbledore learned it."

"Dumbledore's a genius."

Sherlock's raised eyebrow conveyed the obvious riposte.

"Yeah, fine, you are, too, but he's had a hundred years to practice. At this rate you'll be lucky to make it to next week."

Sherlock emitted a bizarre series of hisses until John grabbed him from behind and dragged him across the room.

"Sherlock, I'm serious. Snakes are deaf, it can't even hear you – real Parseltongues must communicate through some kind of natural magic, not actual sounds."

"Wrong again. Snakes aren't deaf, that's just a Muggle myth."

"Yeah, well, Muggle scientists have backed it up with a lot of evidence."

"They've backed it up with a series of laboratory experiments, unaware that the snakes in question were too intelligent and stubborn to respond to every white-coated idiot who whistled at them. Snakes love skewing empirical results. I used to do the same thing to my doctors – diagnostic sabotage is the universal revenge of caged intellect."

"Whatever. Get the killer snake off my bed."

"In a minute. I'm trying to talk it into climbing up the bed curtain."

_The Patronus, Year Five:_

Sherlock was sixteen before he mastered the Patronus Charm.

This was still far in advance of the standard curriculum requirements, but not half so far in advance as Sherlock usually stayed. The problem wasn't that he was never happy, but rather that his happiness was almost always coupled with disaster. His version of joy required a knife's edge; it rarely translated into the soaring hopefulness that defined a proper Patronus.

John had no doubt that Sherlock would manage the charm eventually, and in idle moments he speculated about what form it would take. He could imagine anything from a unicorn to a manticore to a great white shark, but he never for a moment considered that it could be anything less than spectacular. Spectacular was a given.

It turned out to be a sea anemone.

Granted, it was a huge anemone, almost six feet tall, with massive tentacles. But still.

"I feel like I should have seen this coming, somehow," John said, wandering out from the kitchen where Sherlock's Patronus was floating ominously by the sink. He reached for the volume of Encyclopedia Britannica (AL through BA) that the bookshelf had just obligingly sprouted.

"Anemone. An ancient predatory species," John read aloud, "elegant in its biological simplicity. Ranging up to 2 meters, the anemone paralyzes and consumes its prey by excreting neurotoxins through its tentacles. Generally solitary and firmly rooted to the ocean floor, the anemone can, when occasion demands, detach from its original perch and float to new territory. It sometimes functions in symbiosis with a complementary lifeform; in rare instances it attaches itself to the side of a large, living fish. Its usual life cycle includes significant long-term growth and asexual reproduction through the process of budding. Truly one of the wonders of the sea."

"You had me at neurotoxins," Sherlock announced. "Do Dementors have neurons, do you think? Surely they do. To lack a soul might be called a misfortune, but to lack a brain as well would look like carelessness."

The Patronus' tentacles drifted outwards in oddly harmonious motion, as if moved by invisible currents. Both boys gave them a wide berth.

"This beauty won't chase Dementors off, you realize," John pointed out. "It'll just sit there and _eat them_. Which, while brilliant, is also a bit disturbing."

"Wuss."

"Prat." John poured himself a cuppa. "You're not so much about defying despair as feeding on it. Is that the point?"

"Your symbolic imagination is depressingly literal," Sherlock said. "Where's my tea?"

"It's not my fault your Patronus is a Dementor-gobbling cannibal. Help yourself."

"Oh, never mind."

John watched the luminous floating strands for awhile. "The encyclopedia said these things can grow out of the side of a fish. What d'you wanna bet that my Patronus'll be the poor sod of a whale that gets this mess grafted onto him?"

Sherlock blinked lazily. "Symbiosis, John." He made a shooing gesture in the direction of the kitchen.

As it turned out, John's Patronus was a school of anemonefish, so-called because they'd evolved an immunity to neurotoxins. They flitted cheerfully through the forest of tentacles.

The broad black and white stripes along their scales looked like a dozen tiny jumpers.

_Family, Year Six (Sherlock's last at Hogwarts):_

The Chamber of Secrets was open. Sherlock, hot on the trail of its monster, was the second student to be paralyzed. All he'd left behind were some scribbled notes about pipes and roosters – that and an empty shell of a body. Mere transport, just as he'd always said.

John gave the illegible notes to Dumbledore, and within hours the whole school had been briefed on basilisks and a proper antidote was brewing for the victims.

When John was finally allowed to visit the hospital wing, he found Mycroft standing over his brother's bed in placid vigil.

John decided a dose of truth might be the best medicine.

"He's pretty sure you love him."

Mycroft blinked. "He said that?"

"Yeah. But he wants to know who you are when you're alone. When you've got no one to influence."

"As if that's the time I'm most myself? Faulty logic, strange for him. He should know that the times when we have nothing to do are not the times that define us. Quite the opposite, in fact."

"He just wishes he could see you without the act you put on for him. And I must say, it is a bit weird, knowing you're acting, even now."

"This is who I really am. You can't ask me to 'drop my act' anymore than you can ask the same of Sherlock. He can't stop deducing, I can't stop influencing. Even if we managed to succeed in shutting ourselves down temporarily, it wouldn't be _real_. It wouldn't show anything about who we are."

"Why is nothing ever simple with you lot?" John shook his head a little.

"After all this time, that still bothers you?"

"It doesn't bother me that Sherlock reads me. Most people get upset or creeped out; they don't like being at his mercy because he's not very merciful. But you know what? At the end of the day, what he does – it's too perfect to resent. And it's kind of nice, to have someone else cut to the point. I know myself better for knowing your brother. It's good, you know?"

"Good," Mycroft tested the word. "Yes. I see." He brushed a bit of invisible lint from Sherlock's pillow.

"With you, it's a bit harder not to be bothered. Sherlock's easy to trust, 'cause he doesn't hide the inside of his head, he ambushes you with it. Non-stop. It's all about seeing things with him, you get more than you want, not less. But I can't see you; he can't even see you, and that's a bit scary. I know you'll never offend me but I don't know if you'll ever tell me the truth, and I guess that's what makes it hard."

"I am what I am, I can't change. I can't make myself transparent."

"No."

"But I'll never, ever hurt him, and if the world tries, it will have to get through me. Believe that or not, as you please."

John nodded approvingly. Then he tilted his head. "Give us a little glimpse of what you're like when you're alone. No one can read you, so you'll just have to say. When you're in the bath, watching your toes wrinkle up, what do you think about?"

"World domination."

"Besides that."

There was a hesitant pause. "Food?"

"What?"

"I think about food, sometimes."

"Oh, that's marvelous."

Apparently surprised, Mycroft looked over with a smile terribly like his brother's – shy and bright and creaky with disuse. "Is it?"

"Yes. May I tell him?"

"Of course."

"He won't be kind about it."

"I don't care," Mycroft said, and patted his brother's foot where it jutted out from under the blanket.

_One fixed point, Year Seven_

John was home for the holidays, mid-way through his final year, when he first encountered the black limousine.

It shadowed him through his Christmas shopping, and when even the public payphones started baying on his trail he decided to stop fighting the inevitable and climbed in.

Sherlock sat behind the wheel, mobile phone still balanced in his right hand. He looked utterly ridiculous in a chauffeur's cap. John could see red and yellow wires dangling loose from the transmission, evidence of a growing larcenous repertoire. He hadn't known till now that Sherlock could hotwire cars.

They drove to an abandoned car park in silence. The air was frosty between them.

Sherlock killed the engine, but neither moved to get out.

"I was beginning to think you were done with me," John said.

"Done with Hogwarts. Not with you."

"You've had a funny way of showing it this year. I haven't had so much as an owl from you since term started."

"I'm living in captivity. All communications are monitored and I didn't want to show my hand until I was ready to move."

John's resentment evaporated in a burst of concern. "What's going on? Sherlock, are you okay?"

"Far from it. I've been forced to room in the basement of one of Mycroft's satellite offices for the last five months. It's like living in a fishbowl surrounded by extremely observant piranhas."

John rubbed the bridge of his nose. "Is the world ending?"

"Not to my knowledge."

"Are you on drugs?"

"Does nicotine count?"

"I want a straight answer, Sherlock – yes or no?"

"No."

"Then why have you allowed your brother to corral you into his fishbowl?"

"Not to mix metaphors," Sherlock reprimanded, then sighed. "The fishbowl's rent-free. I needed to save up enough money to cover both our ends in a decent flat share; I've found the perfect fit, but you won't be able to pitch in on the rent until your stipends kick in next September."

"Sherlock…you never asked me about rooming together after graduation."

"Should I have? You know I hate going over the obvious."

John made a strange, stifled noise in his throat. "I've got years of training yet," he said slowly, "you know that. I'm applying for internships in trauma and curse breaking and I'm going to be reading in antidotes and anesthetics. My life is going to revolve around uni and hospital, and yours will be all over the city. Maybe all over the world. We're not…we're not going to be Housemates anymore."

"Don't be an idiot, John. I told you I found the flat already, _our_ flat. The Room of Requirement considered our long-term needs, not just our immediate ones. It modeled itself on a real place. We lived in those rooms for years, didn't you notice all the Muggle details, the Victorian architecture, the _light switches_? Why on Earth would we need electricity at Hogwarts?"

"I…never really thought about it."

"You're hopeless. The Room was obviously planning ahead, it knew we'd need to move on eventually so it gave us a guide to the next phase of our career. I've tracked down the matching flat, identical down to the wallpaper and the leaky faucets. It's on Baker Street, not a mile from St. Mungo's, it'll be perfect for you while you work through your internships. And it's far enough from Auror headquarters that I won't be living in their pockets but close enough that they'll be tempted to stop by when they're out of their depth. Which will be always. And to top it all off, I'm pretty sure its current landlord is a serial killer, so once I break his alibi I can probably push through a lease on the cheap."

"I never know when you're kidding."

"I'm not kidding."

They stared at each other, Sherlock's arm hooked over the back of his seat.

John said nothing, but the air around him seemed warmer.

"So." Sherlock prompted. "A life of adventure."

"And study," John warned. "And gainful employment."

"If you must. But mainly adventure. Are you in?"

It was a rhetorical question.


End file.
